Gates is “greatly encouraged” by wide support for enhanced educational benefits for veterans and considers the legislation moving forward “extremely generous,” Morrell said.

“We have no issue with the fact that it is generous. We think our troops deserve to be rewarded for their service,” he said.

But the secretary fears that leading bills moving forward would hurt retention by offering educational benefits after just two years of service, Morrell said. Gates advocates offering enhanced benefits after six years of service to reward servicemembers who opt to re-enlist at least once.

“We are not trying to keep people here forever, but we are trying to create a system in which troops see the benefit of making a career out of the military,” Morrell said. “We make an enormous investment in their careers and their futures, and we think it would be very damaging to the all-volunteer force if they were to leave prematurely.”

That would create big problems to the military, particularly as it confronts the global war on terror. “Now, more than ever, we need to hold on to our superbly trained, battle-tested troops,” Morrell said. “They are the key to victory in this conflict.”

Gates has shared his concerns with Congress and has assured lawmakers he will continue working with them to benefit the troops, “but do so in a way that does not jeopardize our national security,” Morrell said.

The secretary calls it “absolutely imperative” that the enhanced GI Bill includes a provision allowing servicemembers to transfer unused educational benefits to their spouses and children.

Gates first heard that suggestion at a military spouses’ group meeting at Fort Hood, Texas, and pitched the idea to President Bush. The president liked the concept so much that he included it in his State of the Union address in January.

Gates has said believes the measure would boost both recruiting and retention.

About 97 percent of servicemembers sign up for the Montgomery GI Bill, but only about 70 percent actually use the benefit, and typically they use about half of the 36 months of benefits available to them, officials said.